The purpose of the proposed research is to: (1) apply Heart-Rate Audiometry as developed under the present grant to the early detection of peripheral auditory impairment in a population of infants at special risk, and (2) to extend the analysis of auditory function to the study of hemispheric specialization for speech in a subsample of the same special-risk population. Subjects will be the surviving infants of an Intensive Care Unit. All infants will be screened for peripheral hearing loss. Those infants showing loss will be further tested using Brain Stem Audiometry. A special subsample who have been most severely compromised in the neonatal period, but without hearing loss, will be studied for the development of lateralization of speech, using analysis of the ongoing EEG and evoked potentials to linguistic stimuli. It is hoped that this last experiment will contribute to the prediction of developmental delay of language.